William Friedkin returned to Washington last week to talk about his latest project - The Devil and Father Amorth, a documentary project that explores real-life exorcisms.

In it, Friedkin witnesses and films an exorcism in Italy in 2016, of a young Italian woman named Christina who believed that she was possessed. The experience was different from what was portrayed in Friedkin's 1973 classic, The Exorcist, but he says that it was still very chilling.

"I had to consider whether or not I wanted to show this, but I ultimately felt that I had seen it and people should see it," Friedkin tells Variety's "PopPolitics" on SiriusXM.

Several years ago, Friedkin was in Italy and met with Father Gabriele Amorth, then regarded as the foremost Catholic authority on exorcisms, and Amorth agreed to let him witness one and to shoot it, on the condition that it only be with a small camera and no lighting.

"I doubt that there's one percent of people on Earth who have seen an exorcism - a real Roman Catholic exorcism. Most of the priests had never seen it," Friedkin says.

In the documentary, Friedkin shows his footage to a number of university medical professionals, including psychiatrists, and "they have never seen anything like this, and they all said they wouldn't know what to do with this woman. They couldn't operate on her."

The Exorcist featured levitation and head-spinning, and it was a work of fiction. The documentary isn't as physically dramatic, but Christina's behavior is unexplained. She goes into a trance-like state, and as Amorth performs a battery of prayers, she starts becoming agitated, and then has to be restrained as her voice changes to a guttural tone. She yells at him as if they are the words of Satan, as several men restrain her.

One of the doctors Friedkin interviewed has been involved in a brain mapping program. He "said that he had no idea what this was, but said that just because we don't understand something doesn't mean it doesn't exist," Friedkin says. "That is how I come down on possession and exorcisms. I can't say that I understand it. There are no experts. Not even in the priesthood, or at the highest levels of the Catholic Church."

The Exorcist was shot in Georgetown in 1972, and the film crew stayed across the Potomac at the Key Bridge Marriott, the same summer that Bob Woodward was "interviewing Deep Throat in the garage," Friedkin says. George McGovern, then running for president, would come by the home at Prospect and 36th, where scenes were shot, and watched the filming.

In The Devil and Father Amorth, Friedkin goes back to some of the locations, including the famous steps that are now a tourist landmark.

"Not much has changed," Friedkin says of Washington then and now. "It is as politically precipitous today, in a different way, as it was then. Political problems, suspicion of the president of this or that, investigations all over town. Watergate was in the papers every day."